An organic electronic device (OED) is a device which exhibits a function through a charge exchange between an electrode layer and an organic material, and for example, includes an organic light emitting device (OLED), an organic solar cell, an organic photo conductor (OPC), an organic transistor or the like.
An OLED, which is a representative organic electronic device, generally includes a substrate, a first electrode layer, an organic layer including a light-emitting layer, and a second electrode layer sequentially.
In a structure referred to as a so-called bottom emitting device, the first electrode layer may be formed of a transparent electrode layer, and the second electrode layer may be formed of a reflective electrode layer. Further, in a structure referred to as a so-called top emitting device, the first electrode layer may be formed of a reflective electrode layer, and the second electrode layer may be formed of a transparent electrode layer.
Electrons and holes each are injected from the two electrode layers, and the injected electrons and holes recombine in the light-emitting layer to generate light. The light may be emitted to the substrate side in the bottom emitting device, and light may be emitted to the second electrode layer side in the top emitting device.
In the structure of the OLED, refractive indexes of indium tin oxide (ITO) which is generally used as a transparent electrode layer, an organic layer, and a substrate which is generally formed of a glass are approximately 2.0, 1.8 and 1.5, respectively. By the relationship of the above-described refractive indexes, for example, light generated in the organic light-emitting layer is trapped in an interface between the organic layer and the first electrode layer, or in the substrate by a total internal reflection phenomenon or the like, and only a very small amount of light is emitted in the bottom emitting device.